Not sure why anyone downvoted you, but yeah. I even made a comment about it here lol. Spring onions with carne asada, toss some pieces into a corn tortilla with a spritz of lime, and mmm, you got a tasty taco there.
Never done it, usually decomposed into wedges and grilled in a basket with other veggies like garlic, mushrooms, and golden beets. They do it with half onions at a Lebanese restaurant near me they are sweet and delicious!
I personally peal the outer most layer as it's burnt a bit, but some people love it. I like to eat them layer by layer, pealing one at a time. Does that make sense?
That depends heavily on what you plan on serving them with. If it's being served with something that would pair with a cooked and softly charred onion, hell yes.
If you're just planning on eating a whole grilled onion by itself though, you're off your rocker.